It is known in the art that polyurethane resins can be provided with dyeability, moisture-absorbing and other properties by using a high-molecular-weight polyol comprising a sulfonic acid salt group-containing polyester polyol resulting from copolymerization using a sulfonic acid salt group-containing dibasic acid and terephthalic acid and/or isophthalic acid as acid components (cf. e.g. Japanese Kokai Publication Sho-59-6210).